I'm about to embark on a fairly long journey {upcoming post} and as I read the couple of comments on Zzz's cub trip regarding NEVER attaching chains to the wing tie downs it got my gears turning. I've searched BCP pretty extensively and not quite found the answers I'm looking for so here go the noob questions about tie downs. I'm bringing my own gear to go pick up a plane and I want to make sure I'm adequately prepared.

Knots- There appear to be endless thoughts on which knot is good and which knot is not
Is there anything wrong with a good old Bowline knot? I've used them for years on ski boats on wake infested lakes and never had one get away. Does a bowline have qualities which render it less than ideal for aircraft use?

Rope strength- I gather that nylon rope is the way to go but of what strength does it need to be. I say strength rather than diameter since I don't see diameter as any inherent indicator of strength.

Rope length- rather than carrying a 100' wad of rope I'd like to have sufficient rope but no more than necessary. How long should my tiedown ropes be for a Pacer on 8.5's?

Anchors- I have three cork screw type anchors 15" overall shank with about 7" of that being the 1.5" diameter screw. I catch myself thinking that even though they won't pull a truck bumper off, they're better than nothing but..... If they're not enough, fail and cause a bent airplane were they really any better than nothing?

and while we're at it....
Gust locks- I am personally not in favor of control yoke type locks because I feel that they transfer any force to control cables, pulleys and cable attachments not to mention the yoke itself. Obviously they cant be all that bad or else Cessna and who knows who all else wouldn't have designed them in but it's just my preference. I'm contemplating fabricating some of the disk sort which sandwich the control surface to it's stationary neighbor. If I were to do so, how many would be necessary? 2 per aileron 1 for the rudder and two for the elevator? or is 1 per aileron enough? Do flaps need 'em?

I know I'm probably getting way too wrapped around the axle on some of the above points but you never know until you ask right?

Be gentle

SD

I use fly ties and have been happy with them. I added my own nylon rope, not sure which kind but it's higher quality than what you get with the kit. For the length I trimmed it so there's enough to go from the tie down through the eyebolt on the strut and about half the length back down. This leaves enough room to throw in 3 cats paws which work fine most of the time. If it's really windy or I'm leaving the airplane for a while I'll secure it with a truckers hitch, 3 alternating half hitches, and a locking knot in the running end. That won't come out until you take it out. The kit doesn't come with a hammer which is fine by me because I always take a hatchet with me into the backcountry and it serves double duty pounding in stakes and chopping firewood.

http://www.flyties.com

Edit: I was taught this knot when I learned to fly in a J-3 11 years ago... I was under the impression that it was a cats paw but apparently it isn't. It's a "midshipman's hitch"

Fly Ties are the best by far. The claw is not that good as tested by Aviation Consumer and I know of a fellow who lost his airplane at Oshkosh some years back using "The Claw". If you use cork screw type tie downs you might as well tie the airplane down with yarn or kite string because anything stronger is a waste of effort. Cork screw type anchors are pretty much useless.

I use 2 sets of Fly Ties, 2 at each tie down point for a total of 6. Use good rope, enough to double up, probably 15 feet at the wings leaves enough to double up and have enough left over for a GOOD knot, not those quickie knots that seem to be so popular in the aviation world! (the knot above in previous post)

Do not tie the stick all the way back and have elevator full nose up, wind from behind will raise tail and put airplane on its nose.

Yes to gust locks! Sorry, don't have a good recommendation off the top of my head.

Get some Fly Ties!

G44

What I've always used is 50' of 5/8" diamond braid nylon. I cut it into two 20' lengths and one 10' length. When I was parked outside year round, I'd replace the ropes annually. I use bowline knots to attach to whatever is in the ground. Then a running bowline about 2' below the tiedown ring on the wing, run the free end through the tiedown ring, then through the loop of the bowline. That way I can cinch it down, kind of like a simple block and tackle. hold it tight where it runs through the bowline with one hand, and tie it with the other hand using the truckers hitch Robw56 described. This way my tiedowns are always tight, actually under tension. For the tail I usually just use a couple hitches.

What I think is even more important than the knots is looking at the angle of the ropes. I like to have the wing tiedowns angled slightly forward from the wing to the ground, and the tail tiedown back away from the plane. That way no matter which way the wind blows it won't be able to move the plane. I've seen hundreds of planes over the years that pull too far forward and are tied down with the ropes angled back, and a long rope to the tail wheel (if the tail is tied at all). A wind comes along and the plane rolls back and all the ropes then have 2 feet or more of slack.

Using chocks and/or the parking brake helps too, since it will transfer some of the twisting load from a cross wind to the landing gear. This is really important on a nose wheel aircraft, since a wind from behind will cause the plane to roll forward, the tail tiedown lifts the nose and causes the main tiedowns to slacken.

This may be helpful. This is probably the test that G44 was referring to.

+1 for fly ties

bowline knot is a good solid knot - the only downside is the adjustability to get it snug - but it's definitely a lot stronger than the midshipman's hitch which is the standard knot most folks use

throw the corkscrew ones away.. you will anyway when you try to screw them into rocky or hardpan ground... I have fly ties... you can't pull them out and I even use the ropes that came with the kit but nylon would be a better choice but I haven't felt the need to change from the ones in the kit....and I too have a small hatchet in the kit bag...serves a double purpose when camping....one thing I did though was make a loop attached to the tiedown block that gets nailed to the ground... and spliced the end nautical style....

One of the problems I've seen is that there is so much junk rope stock out there.....

I went to REI and purchased some short lengths of climbing rope. Three pieces, two at fifteen feet and one at ten feet. They or any good climbing shop will have bulk rope so you don't have to buy a mile of it....it's expensive, much more so than the hardware store stuff. But, it's designed to carry loads that protect human lives....that suggests that they may make it a bit tougher than hardware store rope, which is made in China, or??

I too like Fly Ties.

I use a bowline at the ground end and an airmanship hitch at the plane end....airmanship hitch is same as others have described...two half hitches, locked with a third. Simple knot, holds well, and most important, it is easy to tighten without having to untie it.

Which brings up a point: If you REALLY want your airplane to be there in the morning, and the wind is REALLY cranking, you need to be out there, baby sitting that plane...tightening lines, checking control locks, etc. And while you're there, keep an eye on the planes around yours....they come loose, and they may take yours with them. Keep airplanes outside on the AK Peninsula and Kodiak for a while and you learn that routine.

If you make small circular gust locks, attach pieces of parachute cord you can secure to some part of the plane to keep them from sliding off as the plane moves around.

One gust lock between flap/aileron on each wing, and one each on counterbalance arm of rudder and elevator.

When I parked outside in Cold Bay and Kodiak, I made a four foot long sandwich of one by fours, padded, that slid over the rudder/stabilizer and another that went over the elevator/horizontal. Attach bolt on one end, wing nut on the other. PITA to carry around, but okay for home.

MTV

Thanks for all the replies guys.

I read loud and clear Flyties. I'll be ordering a set momentarily and will procure 40' of GOOD rope.

I think I remember seeing it covered on BCP somewhere but for the gust locks, is there a preferred material for making the disks?
Is 1/8" or 1/4" plywood ok? I will be covering the contact side with carpet or felt.

I'm certainly not planning to park in a hurricane or anything but it seems silly to risk banging up my investment over something as age old as wind.
I've been a renter for a long time thus never taken planes anywhere that didn't have nicely groomed pavement and tiedowns everywhere.

Thanks again
SD

Rope diameter can be used to determine the strength of a rope provided you know the type of rope you are working with.

For 3 strand nylon, for example, if you square the eighths of the diameter and multiply by 70 it will give you the SWL of that rope.

Dean

Bear in mind that as soon as you tie knots in a rope it reduces the SWL by approximately 50%.

I personally like to use a polyester double braid rope, it is stronger than nylon but has quite a bit less stretch, so I keep it cinched up quite tight when I use it.

I also know of at least 1 flight school at my airport that uses ratchet straps for their tie downs.

Bowline at the ground, airmanship knot at the plane.

Invest in a set of wing covers with spoilers from Alaska Wing Covers.
http://alaskawingcovers.com/

I bought a full set for the SQ-2 (engine - insulated, cockpit, wings, tail, tires). Awesome would be an appropriate description. I ordered the wing covers with colored spoilers, green and red, and they really work. At 3 Mile in Alberta we had moderately strong winds, enough that she was getting excited about flying. As soon as the wing covers went on she sat there quietly. At White Court we got snowed on for three quarters of the day and I sat in the FBO watching the snow slide right off the covers.

Last week I ordered a set of All Season Spoiler Strips for both the SQ-2 and the 185. These covers are just about the spoilers. Again I ordered the spoilers colored green and red.

As far as tiedowns, I carry two types:

Abe's Tiedown System
http://www.abesaviation.com/

And for really hard ground, I can't remember the name, but it's a piece of angle iron with nails.

I was looking at the test videos and it seems that Abe's held the best, and not surprisingly, cost the most.

Could someone please comment on the use of tie-down straps versus ropes.

And Straydog: We need a little more information on this new acquisition!

I saw a neat idea a few months ago.

Bowlines in the anchor ends and bowlines to cinch like Bear Builder suggested, but with D-rings in the line. So it's easy hook up and you don't have to untie the knots, but you get length adjustability at the same time. I wish if have taken a picture.

MAU MAU wrote:I was looking at the test videos and it seems that Abe's held the best, and not surprisingly, cost the most.

Could someone please comment on the use of tie-down straps versus ropes.

And Straydog: We need a little more information on this new acquisition!

Tiedowns need to exhibit a couple of features:

They need to be strong.

They need to give a little bit.

As they give, they protect the airframe from damage due to gust loads......this is why chains are a no no.....no give.

My concern with ratcheting straps is that they won't give much at all. So, the same concerns apply as using chains. Maybe straps give "enough" but from my experience with tying down loads, I don't think they give much at all.

MTV

Mike is right on. Ropes not straps. I prefer 25' foot for all three, they don't weigh anything and that way I don't have to wonder which is for the tail. In the SQ-2 they reside right next to my seat so I can get to them quick. I also keep a set of chocks in the same place - if the wind is really blowing I can drop them behind the wheels without leaving the seat.

Flyties here too. Bowline at the Flytie with double airman's knot at the wing. I run the rope thru the tie down ring, then around the spar and back thru the tie down ring. I went to the climbing rope store and bought the strongest climbing rope they had. It is strong, light weight, easy to tie and has a built in "give" when stressed. Flytie recommends you place them straight down under the wing attach point.

I think ratchet straps and chains are a lot different. With chains they almost always have slack, so when the plane rocks in the wind the damage is done. With a ratchet strap, you can put a bit of pressure on them so they stay tight. I had my Citabria on 31s tied down this way when 120km/hr winds blew through last summer. I was checking it all night, and it never rocked enough for the straps to get any slack. I dont think I couldve gotten that with ropes.
Even if a rope has some stretch, I cant see it being good for a wing to be jerking caused by slack...

The angle iron ones I have are Storm Force.

Haven't been in much wind with them, but I like them so far.

Good discussion and good advice above.

Keep in mind, the best tie down may vary with location. What's great in the grass of ID and OR, may not work well in the sand of UT or the rock of CO. Also, I see a lot of tie downs kits using many stakes, and sometimes it's hard to find an area where all the stakes will go in properly (rocks, roots, etc).

I have found that a 18" concrete rod/stake with a ring/link welded on provides a good overall tie down for challenging environments (thanks HiCountry). Also, 15 ft ropes work well as one may not find suitable ground just under the tie down point of the wing. More rope gives one more options. I have found that soft sand, and hard clay go down to about 6-8", so an 18" stake will penetrate into good solid ground. If it rains, clay will become very gooey and not hold well. With a large steel stake, you can pound away, I've seen a lot of kits use small diameter stakes, and when they hit a rock or root, they bend pretty easily.



I also have a set these and they have been great for overall use. I like the width and that they provide a "spade" like penetration. Also very strong and light. I've used them dozens of times, and they are finally starting to slightly bend at the flange/head, time to pick up another set.



Good rope and good knots are just as important.

If you are planning on only published grass strips and not venturing off airport, I too suggest FlyTies, they are a good company and support the raffle year after year by donating a deluxe kit.